Blood vascular System.ppt by ZubairLatif


More Info
									        The circulatory system
  This is the composite body system
which is responsible for the continuous
movement of all body fluids and their

        Blood vascular system
        Lymph vascular system
• Blood
• The blood vascular system consists of a continuum of
  blood vessels.
• arteries
• arterioles
•  capillaries
•  venules
•  veins
• heart
• The blood vascular system distributes
• nutrients
• gases
• hormones
        Lymph vascular system
• lymph
• Collects tissue fluid from tissues.
• lymphatic capillaries
   lymphatic vessels
  lymphoid organs
    Pulmonary and Systemic Circuits

• Pulmonary circuit – carries deoxygenated blood to
  the lungs then back to the heart.
1. pulmonary trunk
2. Left and right pulmonary arteries
3. Pulmonary veins

• Systemic circuit – carries oxygenated blood to the
  body tissues
  - coronary circuit.
Histological Organization of Blood Vessels

3 distinct layers:
  1. Tunica intima –
innermost layer includes
   Endothelium .
  Sub endothelium.
  Internal elastic membrane.
 2. Tunica media – middle layer contains concentric
 sheets of smooth muscle in a framework of loose CT
 - Muscle fibers encircle the lumen.
  – - External elastic membrane
– . Elastic Component Decrease as we move away
  From Heart.
– Smooth Muscle Increase as we Move Away from
3. Tunica adventitia – CT sheath around the vessels
- collagen fibers with elastic fibers
- fibers blend into adjacent tissues,
  stabilizing and anchoring the BV
- in veins this layer is usually thicker than the
            - The vasa vasorum
            (‘vessels of vessels’)
• BV walls are too thick to allow diffusion
  between the bloodstream and surrounding
• found in large arteries and veins such as the
  aorta and its branches .
• size, function and location of the vessels.
• Controversy?
   Variations of Vessel Wall Structure

• Arteries All arterial vessels originate with either the
  pulmonary trunk (from the right ventricle)
• Aorta (from the left ventricle).
• The Tunica Media is the main site of Histological
  Specializations in the walls of arteries.
• Vessels close to the heart
• Aorta
• Pulmonary trunk
• Larger arteries
 More elastic than distant arteries
         Arteries Organization:
• Elastic arteries

• Muscular arteries

• Arterioles
          Elastic / conducting arteries
•   Transport large volumes of blood.
•   pulmonary and aortic trunks

• Intima
•   thicker than the corresponding tunic of a muscular artery.
•   An internal elastic lamina.

• Tunica media ___High density of
•   elastic fibers.

• 40 - 60 elastic laminae.

•   Elastic laminae , smooth muscle cells, reticular fibers,
•   proteoglycans, and glycoproteins
    walls are extremely resilient.
     Muscular / distribution arteries
•    External carotid , brachial , femoral etc.
• Tunica intima - thin
• (1) Endothelium
• (2) Thin subendothelial layer _fine CF+EF.
• b. Internal elastic lamina - very distinct,
• usually folded
• Tunica media - thick
•    (1) Circular smooth muscle, 5 - 40 layers
•    (2) Small amount of CT with CF +EF.
•    (3) Thickness decreases in small arteries.
•     External elastic lamina.
•    Tunica adventita - thick; loose FECT
•   Structure
•   Diameter below 0.1 - 0.5 mm
•   a. Tunica intima - very thin
•    endothelium +thin sub-endothelium.
•   b. Internal elastic lamina –
     present except in smaller arterioles.

• c. Tunica media - 1 to 2 layers SM.
• d. Tunica adventita - thin,
• longitudinally arranged CF+EF.
• 2. Function –
   To redistribute blood flow to capillaries.
•   Metarteriole.
•    Precapillary sphincters.
•    Capillaries (Surrounded by pericytes)
•    Post-capillary venule (Surrounded by pericytes
    and has the loosest endothelial junction in the
•   system).
•    Collecting venule (Surrounded by pericytes)
•   Small muscular venule
•   Arteriovenous shunts
• Smallest and most delicate blood vessels.
• Approx 8 µm.
•  Their diameter ranges from 5-10 µm.
• Tunica Intima:
  Endothelial cells +BL +Pericytes.
• Tunica Media:
• providing nutrients and oxygen to the surrounding tissues
• the excretion of waste products from the body.
                Capillary Types
•   Continuous capillaries
•   Fenestrated capillaries
•   Porous capillaries
•   Sinusoids capillaries
Continuous (type I)

• - Found in most regions of the body.
  - The endothelium is a complete lining.
  - Endothelial cells are connected by tight
  junctions and desmosomes.
• The endothelial cell + basal lamina
  do not form openings.
• selective filters .
   Fenestrated (type II) capillaries

• The capillary wall is perforated at intervals by
  pores or fenestrations.
• Material cross the cells through the
 GIT + Endocrine glands.
 Larger diameter.
    Porous Capillaries
  Endothelial diaphragm absent.
  Kidney glomerulus.
          Sinusoidal capillaries
• Larger in diameter than the other types.
• Wide spaces between the lateral edges of the
  adjacent endothelial cells
• Materials (and some cells) can move freely in
  and out of the capillary.
• flattened and irregular and follow the internal
  contours of complex organs
• spleen, liver, and bone marrow.
   Distinguishing Arteries from Veins
• Typically arteries supply and veins drain the same
  region lie side by side within CT
• May be distinguished by:
  1. Walls of arteries in general are thicker – tunica media
  contains more smooth muscle and elastic fibers.

  3. endothelium is thrown into folds giving a pleated
 veins lack these folds
• 10 microns to 1 mm.

• Post-capillary venules:
• Larger diameter than capillaries
• consist of endothelium surrounded by pericytes.

• Functions:

• Collect blood from capillaries.
  Site of exchange of materials between tissue fluid and blood
• Site of exit of WBCs from blood into tissue
                    Larger muscular venules

• (1) Tunica intima – thin
• Endothelium surrounded by outer sheath of collagen fibers

• (2) Tunica media – thin
• 1 - 3 layers of smooth muscle (circular) with collagen and elastic fibers
  between muscles

• (3) Tunica adventita – thick
• Loose FECT containing longitudinal collagen fibers and scattered
  elastic fibers and fibroblasts.

•   Function –
•   To collect blood from post-capillary venules
              Small to medium veins

•   a. Tunica intima - thin
•   (1) Endothelium
•   (2) Thin subendothelial layer
•   (3) May be folded to form valves

• b. Tunica media - thin; circular smooth muscle, collagen fibers, some
  elastic fibers

• c. Tunica adventita - well developed
• loose FECT with longitudinally arranged collagen and elastic fibers,
  bundles of longitudinal smooth muscle

• 2. Function - to collect blood from smaller venous vessels
        Large veins - vena cavae and larger branches
•   1. Structure
•   a. Tunica intima - thicker
•   (1) Endothelium
•   (2) Thin subendothelial layer

• b. Internal elastic lamina - usually distinguishable
• c. Tunica media - thin, poorly developed; mostly FECT; little smooth muscle

• d. Tunica adventita - very thick; moderately dense FECT with spirally
  arranged collagen fibers, elastic laminae, longitudinal smooth muscle

• 2. Function - to collect blood from medium sized veins and return it to heart
     Medium to small arteries (also called muscular arteries)
•   Tunica intima - thin
•   (1) Endothelium
•   (2) Thin subendothelial layer .
•   b. Internal elastic lamina - very distinct, usually folded.

• Tunica media - thick
• (1) Circular smooth muscle, 5 - 40 layers
• (2) Small amount of CT with collagen fibers and elastic fibers (longitudinal
  orientation) between muscle
• (3) Thickness decreases as diameter of vessel decreases
• d. External elastic lamina (May be indistinct in smaller muscular arteries)
• Tunica adventitia – thinner than media ; loose FECT

•   Function - to distribute blood to smaller arterial vessels. The muscular
    wall resists damage due to relatively high blood pressure in these vessels

To top